After losing her boyfriend and partner in crime, Rust, during a tragic run-in with security, Metro moves to Berlin to start over. She finds a home in a grimy squat where she befriends other graffiti artists, and together they carry out aggressive attacks, bombing entire trains and buildings with fresh paint and achieving international notoriety by posting their hits online.
Adorning the attic of their squat is a wall-size piece by world-famous tagger Banksy depicting a silhouetted rat spraying a wall. It's a hidden treasure amid the squalor. But when Metro comes home one day to find bodies--including one familiar face from her past--scattered around the building and the amazing mural missing entirely, she and her friends are forced into action. The piece turns up at auction for millions of dollars, and Metro must follow it to its new home in Kotka, Finland, a town she thought she had left behind for good.
Up against the law and on the run from her personal demons, Metro has no choice but to seek justice with the only means she has: graffiti.